Does your toilet smell like rotten eggs? Be careful!

If you smell a pungent smell of rotten eggs in the toilet, be careful! Because the thing that emits this smell is most likely hydrogen sulfide . Hydrogen sulfide, chemical formula H₂S. It is composed of two hydrogen atoms and one sulfur atom. It is a colorless gas and flammable at room temperature and pressure. In our textbooks, it has a special description - "smell of rotten eggs".

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Hydrogen sulfide is one of the main culprits behind the pungent odor in toilets . When we go to the toilet, we have to endure the stench. What's worse is that hydrogen sulfide is also an extremely dangerous and highly toxic gas that can kill people invisibly! If you pay attention to the news, you will know that there are cases of death caused by hydrogen sulfide almost every year.

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01Toilet : A hotbed of hydrogen sulfide

Where does the hydrogen sulfide in the toilet come from?

The hydrogen sulfide in the toilet is mainly produced by the decomposition of organic sulfides, which are mainly derived from the food we eat, especially proteins containing sulfur . These sulfur-containing substances are excreted into the toilet and encounter bacteria in the waterway (sulfate-reducing bacteria and other anaerobic bacteria). These bacteria, like Breaking Bad, cook the organic sulfur into hydrogen sulfide, which is equivalent to a chemical reaction (literally). Of course, along with hydrogen sulfide, there are also trace gases such as ammonia, indole, volatile amines, and volatile fatty acids. They have similar smells and form a strange orchestra in the sewer, playing a symphony of stench.

Hydrogen sulfide is not only found in toilets. Generally speaking, hydrogen sulfide is likely to be produced whenever sulfur comes into contact with organic matter. So it is also found in places such as biogas digesters, wastewater treatment plants, garbage treatment plants, oil or gas drilling and mines . Hydrogen sulfide is denser than air, which causes it to prefer low places and generally gather at the bottom of closed or poorly ventilated places.

When you see this sign appear, be sure to pay attention!

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02How toxic is hydrogen sulfide?

The harm of hydrogen sulfide to humans lies in its ability to damage the respiratory and nervous systems, causing damage to multiple organs such as the eyes, lungs, heart and even the brain . Therefore, continuous inhalation of hydrogen sulfide can cause suffocation and poisoning. The harm caused by hydrogen sulfide to human health depends on the dose and duration of exposure.

At low concentrations, hydrogen sulfide may cause eye and respiratory irritation symptoms, such as eye pain, coughing, and throat discomfort. Usually, these symptoms disappear quickly after exposure stops. At high concentrations, hydrogen sulfide has a more obvious depressant effect on the central nervous system. The following are some relevant dose data:

China's national standard stipulates that the threshold value of hydrogen sulfide is 10ppm. The critical safety concentration is the highest concentration of hydrogen sulfide that workers can accept when working in the open air for 8 hours. The critical safety concentration of hydrogen sulfide is 20ppm. When the concentration of hydrogen sulfide in the ambient air exceeds 20ppm, personnel at the work site should immediately wear a positive pressure air respirator. The olfactory threshold of hydrogen sulfide is 0.003ppm (not absolute). Low concentrations of hydrogen sulfide can also damage people's sense of smell. When the concentration of hydrogen sulfide exceeds 100ppm, it will cause olfactory paralysis. Therefore, try not to use your nose to detect hydrogen sulfide ! You can use a hydrogen sulfide detector to detect the concentration of hydrogen sulfide.

03What to do in a high concentration hydrogen sulfide environment?

If you are accidentally exposed to high concentrations of hydrogen sulfide gas, take the following measures immediately:

1. Leave the danger zone quickly : If you or others are exposed to high concentrations of hydrogen sulfide gas, you should leave the danger zone immediately and stay away from the gas source. Hydrogen sulfide is heavier than air and tends to gather in lower areas, so try to move upward or away from the gas source.

2. Breathe fresh air : Get away from the hydrogen sulfide environment as soon as possible and breathe fresh air to dilute the concentration of hydrogen sulfide in the body. If you have difficulty breathing or other discomfort symptoms, you should find a safe place nearby and avoid continuing to inhale harmful gases.

3. Seek emergency medical help : Hydrogen sulfide poisoning is an emergency situation. You should immediately call the emergency number (such as 120) and inform the medical staff of the relevant situation. The medical staff will provide further guidance and send emergency personnel to rescue.

4. Provide first aid measures : While waiting for the arrival of emergency personnel, some simple first aid measures can be performed, such as cardiopulmonary resuscitation (CPR) or artificial respiration, to help maintain the victim's vital signs. High concentrations of hydrogen sulfide can cause sudden fainting. In hydrogen sulfide poisoning incidents, there are often cases of consecutive deaths! In the case of hydrogen sulfide poisoning, rescuers should avoid inhalation or exposure to avoid tragedy!

04How to avoid hydrogen sulfide poisoning in daily life?

Of course, in daily life, in order to prevent the deadly smell of rotten eggs in the bathroom, we can start with some small things:

1. Ventilation : This is the most effective and convenient method. We can install a ventilation device in the bathroom to blow away the hydrogen sulfide gas in the room. Of course, if you think the ventilation equipment is too expensive, you can also try opening the window to introduce fresh air to drive away the odor.

2. Use deodorant : Deodorant can neutralize the smell of hydrogen sulfide and keep the toilet fresh; choose a deodorant containing activated carbon, oxidants or other adsorbents, which can effectively adsorb and degrade hydrogen sulfide gas.

3. Regular cleaning : By removing dirt and bacteria from the sewer, the generation of hydrogen sulfide can be reduced. Using appropriate detergents or biological enzyme preparations can effectively decompose organic matter and prevent the generation of hydrogen sulfide.

4. Check the patency of the sewer : A blocked sewer will cause sewage to stagnate and increase the generation of hydrogen sulfide. Therefore, regularly checking the patency of the sewer and clearing the blockage in time is an important means to prevent hydrogen sulfide problems.

References

[1] Reiffenstein RJ, Hulbert WC, Roth S H. Toxicology of hydrogen sulfide[J]. Annual review of pharmacology and toxicology, 1992, 32(1): 109-134.

[2] Guidotti T L. Hydrogen sulfide: advances in understanding human toxicity[J]. International journal of toxicology, 2010, 29(6): 569-581.

[3] Wang Xijing. Be careful when you smell rotten eggs, hydrogen sulfide can kill you [J]. Jilin Labor Protection, 2021.

[4] National Standard “Occupational Exposure Limits for Hazardous Factors in the Workplace Part 1: Chemical Hazardous Factors” (GBZ 2[1].1-2007)

[5] Another 4 lives lost! How to solve the problem of blind rescue? https://baijiahao.baidu.com/s?id=1776368938256630707&wfr=spider&for=pc

Author: Ji Minghua, PhD, Shanghai Advanced Research Institute, Chinese Academy of Sciences, R&D Director, Shanghai Qingrui Food Technology Co., Ltd.

Editor: He Huizi